Liquid crystal display (LCD) is a popular electronic apparatus, and the LCD has many advantages, such as, low power consumption, a small size, and light in weight. Thus, the LCD is welcomed by users. In existing technology, thin film transistor (TFT) LCD is a main kind of LCD. With a development of flat panel display technology, a request that the LCD having a high resolution and a lower power consumption is put forward. Amorphous silicon has a low electronic mobility. The LTPS can be manufactured in a lower temperature than the amorphous silicon, and the LTPS has a higher electronic mobility than the amorphous silicon. Furthermore, a complementary metal oxide semiconductor (CMOS) component made by the LTPS can be applied on the LCD, and the LCD using the CMOS component made by the LTPS has a high resolution and low power consumption. Thus, the LTPS is widely used and researched.
Currently, methods for manufacturing a LTPS film include a solid phase crystallization (SPC) method, a metal induced crystallization (MIC) method, and an excimer laser annealing (ELA) method, and etc. The ELA method is a most popular method in manufacturing a LTPS film. Manufacturing the LTPS film by using the ELA method is described in detail as follows. An amorphous silicon film is shined by an excimer laser beam, and melted by a high temperature generated by the excimer laser beam, and a LTPS film is formed by a recrystallization of the melted amorphous silicon film.
A size of a crystalline grain of the LTPS film has an important effect on an electrical property of the LTPS film. For example, the size of the crystalline grain has an important effect on the electrical property of the LTPS film. When the size of the crystalline grain is large, the LTPS film has a high electronic mobility. When the size of the crystalline grain is small, the LTPS film has a low electronic mobility. In the ELA method, an amorphous silicon film is shined by the excimer laser beam, and melted by a high temperature generated by the excimer laser beam, and the LTPS film is formed by a recrystallization of the melted amorphous silicon film. When the LTPS film is formed by a recrystallization of the melted amorphous silicon film, a direction of the recrystallization is from a low energy to a high energy, a low temperature to a high temperature. In the ELA method in the existing technology, the excimer laser beam uniformly shines on the amorphous silicon film, thus the temperature of each part of the amorphous silicon film is roughly equal. Thus, a starting point and a direction of recrystallization are disorder and irregular, which may cause a small size of the crystalline grain of the LTPS film, and more crystalline grain boundaries of the LTPS film. The electronic mobility of the LTPS film is low.